This invention relates to metal working amd more specifically to the construction of cutting tools such as those producing desired shapes from blanks by removing chips or curls by movement of a cutting face substantially perpendicularly across the blank. For convenience these tools will hereinafter be referred to as chip removing cutters.
Chip removing cutters comprise lathe tools, shaper cutters, shaving dies, saws, milling cutters, hobs and the like. They are distinguished from knives, line dies, shears, punches, punch and die block combinations, and the like, that do not ordinarily remove chips or curls to produce a desired shape.
Gear shaper cutters have been made with relatively thin webs supporting a thicker annular rim, the outside of which is ground to the contour required to produce a desired gear or other shape while one end of the rim acts as the cutting face. The inside of the rim has been cylindrical. Such construction resulted in a limited saving of material.
Metal cutting blades are usually made of solid tool steel, cemented carbide, or other extremely hard materials suitable for such use. These cutting materials are relatively difficult to shape and are quite expensive. Cemented carbides are very brittle, making necessary a back-up support by a more resilient material. For these reasons, it has become common to make cutting blades of cutting material and to affix them permanently or separably to less expensive materials comprising a major portion of the cutting tool. Tool steels have been available in solid bars and plates, while cemented carbides have been available in relatively small flat pieces. The tool steel or cemented carbide raw stock has been cut and/or ground to the desired cutting tool shape with the production of substantial quantities of waste. With the recent introduction of suitable powdered metallurgy techniques, it has become possible to obtain roughly formed blades of high density sintered powdered tool steels that are equivalent or superior in properties to the same material in wrought form. This resulted in a substantial reduction in the cost of raw material, even though the sintered material cost more per unit of weight. It also greatly reduced the time and energy required to finish the blade, resulting in a further cost reduction for labor, machine time and energy. The reduction in machine time further resulted in more blades being produced before the production tool required sharpening or dressing. Cemented carbide pieces have been produced with countersinks for heads of fastening screws and the like.
Abbott in U.S. Pat. No. 1,286,194, issued on Dec. 3, 1918 disclosed bail-shaped metal strip supported at each end on a rotatable body and bent to cut a desired shape in plaster, terra cotta, cement or clay. The strip was unsupported between its ends and would not be sufficiently rigid to cut most solid metals.
Further reductions in cost are desirable.